In the construction of flat concrete surfaces, such as aircraft runways, taxiways, parking aprons, and other concrete structures it is common to divide the surface into a number of individual slabs that are separated by expansion joints. Adjacent slabs are typically coupled to one another by dowels that extend across the expansion joints. The dowels help to transfer loads between adjacent slabs and to control relative movement of the slabs. Conventional concrete dowels have been provided as elongate metal rods or flat metal plates. Regardless of whether rods or plates are used as dowels, a void must be formed in each concrete slab to receive a portion of the dowel. Such voids are typically formed in wet concrete, either at the time of pour, by attaching void formers to the inner surface of concrete edge forms, or after the edge forms have been removed, by inserting void formers into the still wet concrete.
A drawback of previous methods and apparatus for forming voids in slabs is that it is very difficult to remove the void formers from the concrete after the concrete has cured. This is due primarily to the surface adhesion between the concrete and the void former and is particularly problematic for void formers used to create flat-shaped slots in concrete slabs for receiving load plates. Even when void formers are made from plastic, which does not bond to the concrete, surface adhesion between the concrete and the void former makes it difficult to pull the void former from the concrete.
There is thus a need for a void former for creating flat-shaped voids in concrete slabs which overcomes drawbacks of the prior art, such as those described above.